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Model output discussion - heading into 2018


Paul
Message added by Paul

Please only post model discussion in here. 
For more general chat and banter, moans and ramps, please head to the banter thread.
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Posted
  • Location: Scouthead Oldham 295mASL
  • Location: Scouthead Oldham 295mASL
Just now, bluearmy said:

It's a mean chart at 13 1/2 days range. It's nothing more  than an indication of the likely upper air flow and potential anomoly location. View in conjunction wit the clusters in five minutes.  I think you should give it a few days to consolidate before making a forecast for jock's back garden !!!

and yep, the ec 46 looks pretty dire, especially weeks 3 and 4 (not that bothered re 5 and 6 anyway). Awaiting the global view to put the Icelandic into perspective 

Sorry Blue i didnt realize i thought that was a chart from next week!!

Im a bit confused tho...the EC46 looks horrendous but the ext eps are euro troughy..

 

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Posted
  • Location: Scouthead Oldham 295mASL
  • Location: Scouthead Oldham 295mASL
2 minutes ago, feb1991blizzard said:

No, this is derived from the 0z run though, so what we need is that the 12z has picked up on a new trend and that continues on the overnight runs, thus rendering that poor EC46 run 7 irrelevant and that xmas days run will then flip.

Gotya...cheers Feb...

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Posted
  • Location: st albans
  • Location: st albans
4 minutes ago, northwestsnow said:

Doesnt tie in withe euro trough on the ext eps then!!

Well it is covering days 18 to 25 as a mean .......... and the 00z eps were less troughy than the 12z so IF there is new data making a difference the ec46 could already be out of date!  

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Posted
  • Location: Scouthead Oldham 295mASL
  • Location: Scouthead Oldham 295mASL
Just now, bluearmy said:

Well it is covering days 18 to 25 as a mean .......... and the 00z eps were less troughy than the 12z so IF there is new data making a difference the ec46 could already be out of date!  

Yes makes sense now...

With all the data to hand i would question (or rather be very sceptical)of anything showing a euro trough longer term.

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Posted
  • Location: Hoyland,barnsley,south yorkshire(134m asl)
  • Weather Preferences: severe storms,snow wind and ice
  • Location: Hoyland,barnsley,south yorkshire(134m asl)
7 minutes ago, Longtimelurker said:

I never said it was useless so don't put words in my mouth. I'm not expecting a silver bullet either. My point is it gets mentioned more than anything else when it comes to signals on here and almost always some excuse is made for it when it doesn't pan out as expected, a wishy washy non descriptive one at that . I'm not railing against anything just pointing out the jibberish and your post would be well suited to the moan thread. How dare anyone on here question background signals. How very dare they. 

I think you are being a bit unfair there Longtime>lurker

no model is infalable nor is the teleconnections and background drivers,Pual was just illustrating that the mjo is one part of the parcel in trying to determine where we go in the med-long tern,there are other factors/drivers that can overide this,nobody is perfect and noboby will be,it's the way of the game in meteorogical terms

so don't shoot the bullet and you won't get wounded:)

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Posted
  • Location: Drayton, Portsmouth
  • Location: Drayton, Portsmouth
52 minutes ago, FiftyShadesofWine said:

No they've been poor, since I gave Feb the link, the flip flopping is awful...iv stopped posting them, they fluctuate from troughing to ridging far too often. The 10-15 period lately has been way out if you study them morning an evening. Remember they showed fantastic Scandy highs for a while....Scandy highs, we have nowt.

That is wrong. The EC clusters are freely available for every run for the past 6 months - they can be checked easily - and they have never shown a Scandi High in the 10-15 period except within a couple of outlier clusters? What are you basing your idea on? If it's the mean, well I haven't been following that, but the clusters have been a virtual empathetic "no" to the Scandi High every time.

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Posted
  • Location: Lincolnshire - 15m asl
  • Weather Preferences: Frost and snow. A quiet autumn day is also good.
  • Location: Lincolnshire - 15m asl
2 hours ago, Paul said:

This isn't specifically aimed at you, but way too many are falling into the trap of expecting a silver bullet when it comes to forecasting - short or long range. The MJO is an indicator, one possible signal to use in amongst 100 others.

It's never been and never will be the single answer to the weather forecast, so to say it's useless because it can be over-ridden or muted is pretty much the equivalent of saying using air pressure in forecasts is useless because you expect it to always be sunny when pressure is high. If forecasting were that simple, we'd have next to nothing to discuss in here!

Weather is complex, rather than railing against the complexities and difficulties of forecasting, i'd recommend embracing it, and trying to learn why things over over-ridden, why some indicators fair well sometimes and not at others, that's the challenge and interest of it all. Failing that, there's always the moans thread :D 

That’s pretty much hits the nail on the head. The more one looks at global weather the more one comes to realise that it is a very complex web of interconnected aspects...and macro as opposed to micro forecasting is a matter of taste. I enjoy the big scale macro patterns...

I’m on an iPad in a hotel in Leeds and away from all my links... but two comments tonight:

1. MJO forecasts are fading fast, but observed as opposed to predicted magnitude still seems disconnected to me. However even taking into account a possible underestimation of amplitude we have begun to see some gloomy suggestions of westerly influence. The trop influence on the strat is flipping just at the wrong time - downwards propagation of strat anomalies now the dominant player and this timing perfectly with a return to the pole of the main start vortex after spending much of December displaced to Asia. End result, taking into account lag time, would be a growing trend for Atlantic awakening... and right at the time the Pacific signal wanes. One wonders whether this is “luck” or whether it is another part of the intricately linked global climate system referred to Paul above. As such I will do what I always do - look at the changes to these key drivers and try and make sense of them. NWP simply reflects these drivers so on its own will teach us little.

Edited by Paul
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Posted
  • Location: Drayton, Portsmouth
  • Location: Drayton, Portsmouth

Speaking of the clusters - just the hint of a height rise to our north / trough to the south at D12 on 2 of the 4 clusters but not noteworthy enough to shout about. Serves me right for only inspecting the individual ensembles at D10 and D15 for my post two hours ago, when the interesting bit was in between!

ec-ens_nat_z500scenarios_2017122112_300.

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Posted
  • Location: Drayton, Portsmouth
  • Location: Drayton, Portsmouth
28 minutes ago, FiftyShadesofWine said:

Don't worry fella, the ext eps are so consistent the next 3 months are nailed on....oh hold on the 00z are less troughy than the 12z...you couldn't make this up.

The way to evaluate ensemble runs is to look for a trend that lasts a couple of days. Take 4 or 5 runs in sequence and I bet you'll usually be headed in the right direction. I think my first response to you tonight proves that.

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Posted
  • Location: st albans
  • Location: st albans
25 minutes ago, FiftyShadesofWine said:

Don't worry fella, the ext eps are so consistent the next 3 months are nailed on....oh hold on the 00z are less troughy than the 12z...you couldn't make this up.

That's odd - you clealry are making most of it up ...............

the clusters reveal less of an appetite for heights to drop tomour south than the mean may have led us to believe but as this is a potential departure from previous extended guidance, it may be worth a wait for the 00z suite.

steve - I am always intrigued when the upper vortex ebbs and flows to extremes. Thus far it's been displaced at 40N up top but it's headed towards 60N and this obviously ties in with the uptick in U wind. if it's forecast to pull back again quite quickly, I always feel there is a chance that the 'foundations' may not be strong enough to support this.  Laymans terms I know but you ge the gist. 

 

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Posted
  • Location: st albans
  • Location: st albans

The ec 46 weeklies are even worse when viewed from a global perspective  .......  roll on Xmas evening when this run will consigned to the bin! 

Of course they could be right ....................

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Posted
  • Location: Heckmondwike, West Yorkshire
  • Location: Heckmondwike, West Yorkshire
3 minutes ago, bluearmy said:

The ec 46 weeklies are even worse when viewed from a global perspective  .......  roll on Xmas evening when this run will consigned to the bin! 

Of course they could be right ....................

Not great news but thanks for posting this anyway. We have to hope the 12z run has sniffed something! 

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Posted
  • Location: Scouthead Oldham 295mASL
  • Location: Scouthead Oldham 295mASL
1 minute ago, bluearmy said:

The ec 46 weeklies are even worse when viewed from a global perspective  .......  roll on Xmas evening when this run will consigned to the bin! 

Of course they could be right ....................

Well from what i can make out from your posts and steves post earler (rgd zonal winds in particular) it sounds very much like a batten down the hatches period coming up..

I think its as near as nailed on as you can possibly get that the next 2 weeks minimum is a write off,certainly as far as any HLB 's are concerned capable of influencing western Europe.Its a sobering analysis but its probably about right.

Fortunately its only the 23rd of December as i type so with a it of luck things might look different in a couple of weeks time..

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Posted
  • Location: Heckmondwike, West Yorkshire
  • Location: Heckmondwike, West Yorkshire
2 minutes ago, northwestsnow said:

Well from what i can make out from your posts and steves post earler (rgd zonal winds in particular) it sounds very much like a batten down the hatches period coming up..

I think its as near as nailed on as you can possibly get that the next 2 weeks minimum is a write off,certainly as far as any HLB 's are concerned capable of influencing western Europe.Its a sobering analysis but its probably about right.

Fortunately its only the 23rd of December as i type so with a it of luck things might look different in a couple of weeks time..

It's 21st Dec but don't worry, I know you can't wait for Christmas lol. Anyway, I happen to think early Jan won't be the right off most on here seem to think. I remember the early to mid 80's winters when a potent cold spell was often preceded by a polar maritime spell. The classic forecasters would often say "if you think it is cold now, wait until next week" :)

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Posted
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)
39 minutes ago, Steve Murr said:

however in the past 5-7 days the GFS peak forecasts for the zonal wind have continually increased - & now see the crest just 2 or 3 M/S slower than the all time strat record- in this case then its total wipeout for Northern blocking- you can liken the speed to the most positive AO phases of the 90s or the December not to remember a couple of years a ago.

So the expectation has changed now & the  GFS 16 day ensembles all have a high peak of zonal winds for the start of Jan - however a sharp gradient of decline in Jan back to below ave levels.. so based on that week 2/3 may yield a high prospect of HLBs

until then - continual battering of westerly winds will be in offering often storm force straight through the nose of the UK.

Can't argue with that, certainly the +PNA / -EPO ridging helped amplify the flow enough downstream to bring so many northerlies in 2nd half of November and into early December I lose count! That was when the troposphere wave patterns were ruling the show, but like you say, it looks increasingly like the uptick in zonal winds in the stratosphere are downwelling to influence the tropospheric flow as we end the year. The cross-polar ridging over into Greenland from the anomalous -EPO ridge perhaps the 'last gasp' from the tropospheric wave  influence over the AO domain, before the SPV looks to return from displacement back to its more usual home over the pole as we head into the New Year.

However, given the eQBO and fall toward solar min, I'm of the optimism that the seasonal cooling and strengthening of the strat PV and its coupling with the trop may not be long-lived and that we may see the SPV weaken and perhaps displace again, even could see signs toward a SSW late Jan, but this a great unknown for now. Kyle Henry earlier today mentioned the potential of tropical cyclone activity recurving and throwing a lot of energy toward the pole on the N Pacific side which may cause further warming over the AO domain.

So, I agree, first half of Jan maybe hard to swallow, given we will likely see a zonal outlook for a few weeks at least. But, we surely can't have such a long run of winters without HLB coming along, and the eQBO this year compared to wQBO in recent few winters would favour this more through a weaker SPV.

Edited by Nick F
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Posted
  • Location: Heckmondwike, West Yorkshire
  • Location: Heckmondwike, West Yorkshire
6 minutes ago, blizzard81 said:

It's 21st Dec but don't worry, I know you can't wait for Christmas lol. Anyway, I happen to think early Jan won't be the right off most on here seem to think. I remember the early to mid 80's winters when a potent cold spell was often preceded by a polar maritime spell. The classic forecasters would often say "if you think it is cold now, wait until next week" :)

For the none believers, take a look at the the gfs 18z control run :)

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Well the GEFS Control Run this evening shows us how rapidly a Scandinavian Anticyclone can develop out of the blue. Well into the very unreliable period and looks like a pub run special but fascinating to watch it develop. Very low 850s just to our east but it doesn't get particularly cold over here. The HP is still around over a week later. I will be doing a report of current and predicted temperatures before Christmas.

                          T+192                                                 T+216                                                T+252                                               T+276

gensnh-0-1-192.png   gensnh-0-1-216.png  gensnh-0-1-252.png  gensnh-0-1-276.png 

                            T+384                                                 T+276                                              T+276                                                T+276

 gensnh-0-1-384.png   gensnh-0-3-276.png   gensnh-0-0-276.png   gensnh-0-4-276.png

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